Exotoxins, Endotoxin and How Damage Is Actually Done · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Two ways germs poison you

Science · Microbiology · ages 20-22
Name ______________________   Date ____________

  1. Which statement describes endotoxin?

    • A secreted protein aimed at one host process
    • Lipid A from Gram negative membranes, spilled as cells break apart
    • An enzyme that dissolves tissue barriers

  2. Which statement describes an exotoxin?

    • A protein released by a living cell that hits one precise target
    • A membrane lipid spilled when Gram negative cells break apart
    • A capsule that shields germs from phagocytes

  3. Boiling destroys exotoxins but not endotoxin. Why?

    • Endotoxin hides inside capsules where heat cannot reach
    • Boiling is too brief to affect any toxin at all
    • Exotoxins are proteins that heat unravels, while endotoxin is a tough lipid

  4. Cholera germs stay in the gut, yet the damage is huge. Why?

    • Their toxin locks gut signaling on and floods the gut with water
    • Their capsules block all immune cells at once
    • Their endotoxin survives boiling and poisons the whole body

  5. Diphtheria starts in the throat but harms the heart. How?

    • The germs swim from the throat into the heart
    • Endotoxin from capsules drifts into the blood
    • The released toxin travels and halts protein synthesis far away

  6. A patient with a Gram negative infection gets a cell bursting antibiotic, then spikes a fever. What happened?

    • The antibiotic directly raised the body temperature
    • Spilled endotoxin triggered an immune overreaction before recovery
    • Exotoxins became heat stable inside the blood

  7. Antitoxin antibodies can help against an exotoxin disease even while antibiotics handle the germs.

    Circle one:   True   False

  8. A lab must reuse tools exposed to each toxin type. What follows from their heat rules?

    • Both need only standard boiling, since all toxins are proteins
    • Standard sterilizing handles exotoxins, but endotoxin needs harsher treatment
    • Neither can ever be removed, so every tool must be thrown away
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Two ways germs poison you W1-mt_RhMqBY_YhR-s1

  1. Lipid A from Gram negative membranes, spilled as cells break apart · Endotoxin is membrane lipid set free by disintegration. Secreted proteins and enzymes are different tools.
  2. A protein released by a living cell that hits one precise target · Exotoxins are secreted proteins with one precise target. Membrane spill and capsules belong elsewhere.
  3. Exotoxins are proteins that heat unravels, while endotoxin is a tough lipid · Heat unravels proteins, so exotoxins fall apart. Lipids shrug off boiling, so endotoxin survives.
  4. Their toxin locks gut signaling on and floods the gut with water · One toxin switching one signal fully on explains the flood. The germs never need to leave the gut.
  5. The released toxin travels and halts protein synthesis far away · The germs stay local while the secreted toxin travels. Distant harm with a local infection means exotoxin.
  6. Spilled endotoxin triggered an immune overreaction before recovery · Bursting cells dump endotoxin into the blood. The fever is the immune overreaction, not the drug itself.
  7. True · Antitoxin neutralizes the traveling toxin while antibiotics clear the source. Each covers a different half.
  8. Standard sterilizing handles exotoxins, but endotoxin needs harsher treatment · Protein exotoxins yield to heat, while lipid endotoxin survives it. One rule cannot cover both.
Worksheet · LightMySky